The Increasing Demand for Telecommunications Services
Over the past few decades, the demand for access to information has increased dramatically. Although conventional wire and fiber landlines, cellular networks and geostationary satellite systems have continued to expand in an attempt to meet this relentless growth in demand, the existing capacity is still not sufficient to meet the burgeoning global appetite for telecommunications services.
In European Patent Application EP 365-885-A, and U.S. Pat. No. 5,410,728 Bertiger et al. disclose a Satellite Cellular Telephone and Data Communications System. This system, known as Iridium.TM., comprises 48 low Earth orbit satellites. These satellites communicate with gateways and terminals on the ground and among each other via intersatellite links. Unlike a store-and-forward system, Iridium.TM. is designed to provide real-time service.
Several previous efforts to enhance worldwide communications capabilities are briefly described below. Robert R. Newton disclosed a Multipurpose Satellite System in his U.S. Pat. No. 3,497,807. Newton describes a system in which "any point on Earth is always within the line of sight of some satellite and any satellite is always within the line of sight of an adjacent satellite in the same orbital plane." See Newton, Column 2, Lines 4-7.
U.S. Pat. No. 4,135,156 by Sanders et al., entitled Satellite Communications System Incorporating Ground Relay Station Through Which Messages Between Terminal Stations Are Routed, contains a description of a "satellite relay communications system" that "includes a ground relay station arranged so that each message from one subscriber to another is relayed by the satellite relay to the ground relay, processed by the ground relay and then transmitted to the second subscriber by way of the satellite relay." See Sanders et al., Abstract, Lines 1-6.
Paul S. Visher disclosed a Satellite Arrangement Providing Effective Use of the Geostationary Orbit in his U.S. Pat. No. 4,375,697. His Patent recites a "satellite squadron or cluster formation" which "is disposed in a predetermined location in . . . geostationary orbit . . . ." See Visher, Abstract, Lines 1-2.
In their U.S. Pat. No. 5,119,225, Michael Grant et al. explain their Multiple Access Communication System. The inventors disclose a system that incorporates "a node spacecraft" in geostationary orbit that works in combination with "several user spacecraft" in low Earth orbit. See Grant et al., Abstract, Lines 1-3.
The history of mobile communications can be seen as an effort to make service widely available on both a geographic and economic basis. Early mobile communications systems served the needs of individual companies on a private basis. Through technology advances and regulatory changes, mobile communication services were offered on a commercial basis and grew to meet city, regional, national and even international coverage needs through interconnection to public networks. As part of this evolution, wireless network standards have developed, on both a national and international basis, although there are still no truly international seamless wireless networks.
As mobile communications networks have expanded geographically, prices for equipment and services have fallen dramatically. The decline in price of mobile services is one of the most important forces helping mobile communications reach broad-based markets and demonstrate rapid subscriber growth. The forces driving development of terrestrial wireless communications include:
Advances in Technology:
Advances in radio propagation management, computer micro-processing, the ability to interconnect networks and miniaturization have all combined to make more efficient use of spectrum and to lower equipment and service prices.
Declining Prices:
As production increases for infrastructure and terminal equipment, manufacturers experience economies of scale which lead to lower prices for equipment.
Digital Technology:
Digital technology is replacing analog technology in almost all wireless communication services. The switch to digital technology allows higher subscriber capacities to be served, enhances services and lowers the cost per subscriber for operators.
The resulting reductions in service and equipment cost attributable to the factors described above have allowed mobile communications to penetrate both business and consumer markets. The ultimate goal of wireless services is to provide two-way, ubiquitous, affordable communications services. It was only very recently, with the introduction of mobile satellite services, that this has been made possible. Indeed, mobile satellite services are the final step in the evolution of wireless communications service and are the only services which can provide this ultimate goal of ubiquitous wireless communication.